| Background and ObjectiveChina is a country with a high incidence of lung cancer.Statistics on cancers in recent years have been collected.New cases of lung cancer and deaths are at the top of malignant tumors.In recent years,lung cancer patients have become younger.For patients with advanced lung cancer,especially those with brain metastases,the 5-year survival rate is less than 10%.At the same time,advanced lung cancer seriously affects the quality of life of patients.Therefore,early detection of diseases,accurate diagnosis and timely treatment are particularly important for improving the quality of life of patients and reducing social burden.Currently,X-ray and CT scans are commonly used in the examination of pulmonary lesions.The X-ray is an ordinary screening method.It is not as sensitive to small lesions as CT.CT can show the position,size,shape,and enhancement characteristics of the lesions.Based on this,the type of lesions can be inferred.For some malignant tumors,the extent of enhancement is similar to that of granulation tissue and vascular benign nodules.Magnetic resonance imaging can be used as a supplement.In recent years,with the improvement of people’s living standard,radiation damage caused by X-ray and CT examination has gradually aroused people’s attention.MRI acquires images by stimulating hydrogen protons in the human body.It has the characteristics of high soft tissue resolution and is widely used in the central,digestive,urinary,and musculoskeletal systems.In the past,it was considered that respiratory imaging,heart beats,and tumor-to-lung tissue interface magnetic susceptibility artifacts caused poor imaging of the lungs;with the improvement of magnetic resonance hardware performance,the application of ECG and respiratory triggering techniques,scanning With the improvement of the sequence,lung magnetic resonance imaging research has shown an increasing trend in recent years.Diffusion-weighted MR imaging can reflect the Brownian motion of water molecules in biological tissues.For different types of biological tissues,the internal water molecules are not in the same state of motion.At present,this technique is widely used in central,breast,liver,etc.,for tumor identification and classification.All have a certain significance.However,traditional diffusion-weighted imaging is a mono-exponential model,reflecting the inaccurate movement of water molecules in tissues.In order to more accurately reflect the diffusion of moisture within the tissue,a biexponential model was subsequently proposed.The biexponential model holds that the movement of water molecules in tissues should be divided into true diffusion and micro-circulation perfusion,excluding the effects of micro-circulation perfusion.This model can theoretically reflect the movement of water molecules in tissues more realistically.However,the movement of water molecules in tissues is a dynamic process.The existence of protons constantly exists between real diffusion and micro-circulation perfusion.In order to overcome these problems,a stretched-exponential model is subsequently proposed.This study included 60 patients with pulmonary lesions,analysis of clinical data,pathological and magnetic resonance image,to explore the value of the parameters of the biexponential model and the stretched-exponential model in the diagnosis of benign and malignant lung diseases,the relationship between the parameters,the parameters Diagnostic efficacy in differential diagnosis of benign and malignant lung lesions.Material and Methods60 patients were enrolled in our hospital from February 2016 to February 2018.All patients underwent CT scans in this hospital or in other hospitals to find lung lesions.They were examined with by GE 750 3.0 T high-field magnetic resonance in our department.ALL patients scan the routine axial T1 WI,axial T2 WI FS,multi-b values sequence,a total of 60 lesions were included in this study.The MR datas were sent to GE Advantage Windows 4.5 workstation.Multi-valued image parameters were calculated by using the MADC module in the Function Tools software.Parameters of benign lung lesions and malignant lesions were measured respectively,slow component of diffusion(ADCslow),fast component of diffusion(ADCfast),perfusion fraction(f),diffusion distribution coefficient(DDC),diffusion heterogeneity coefficient(α).The parameters were imported into statistical software SPSS 21.0 for analysis.The parameters were tested for both normality and homogeneity of variance.The parameters that met the normal distribution and homogeneity of variance were compared by independent sample t test.The parameters that do not met normal distribution or variance were compared using the Mann-Whitney U test.The receiver operating characteristic curve(ROC curve)was used to calculate the area under the curve,determine the best critical value of each parameter and evaluate the diagnostic efficacy of each parameter used alone and in combination with the diagnosis of benign and malignant lung lesions.Spearman rank correlation was used to analyze the correlation between the parameters.Results1.Differences of biexponential model parameters in benign lesions and malignant lesions of the lungThe ADCslow,ADCfast,and f values in the benign group were all greater than those in the malignant group.The differences in parameters ADCslow and f were statistically significant(P = 0.000,P = 0.002),and there was no significant difference in the parameters of ADCfast(P = 0.076).2.Differences of the parameters of stretched-exponential model in benign lesions and malignant lesions of the lungThe values of DDC and α in the benign group were higher than those in the malignant group.The differences in parameters DDC and α were statistically significant(P = 0.000,P = 0.002).3.Diagnostic efficiency of parameters of biexponential and tretched-exponential modelPlot ROC curve of the biexponential model parameters ADCslow,f and the stretched-exponential parameters DDC.The area under the curve(AUC)was 0.880,0.666,0.812,and 0.746,respectively.The parameters were the most significant in differentiating benign from malignant lung diseases.The best cut-off values were 1.14×10-3mm2/s,36.35%,1.832×10-3mm2/s,and 0.729 respectively.The sensitivity of each parameter was 77.3%,68.2%,63.3%,and 72.7%,respectively.The specificity was 84.2 respectively.The positive predictive values were 86.5%,78.8%,81%,and 81.8%,respectively.The negative predictive values were 77.3%,55.6%,77.8%,and 59.3%,respectively.4.Multi-parameter combined identification of the diagnostic efficacy of benign and malignant lung lesionsPlot multi-parameter combined ROC curves.When the ADCslow,DDC,α,and f parameters are combined,the ADCslow,DDC,and α parameters are combined,and the ADCslow and DDC parameters are combined,the AUC is 0.916,0.915,and 0.890,respectively;the sensitivity is 97.4% and 92.1%,respectively.,89.5%;specificity was 72.7%,81.8%,72.7%,positive predictive value was 86%,85.7%,80%,negative predictive value of 94.1%,89.7%,85%.5.the correlation between the parametersThere was a positive correlation between ADCslow and DDC values in the lung benign and malignant lesions(r=0.578,P=0.000).The value of f was positively correlated with DDC(r=0.323,P=0.012).ConclusionsThe biexponential model parameters of ADCslow,f and the stretched exponential model parameters of DDC,α have important diagnostic value in differentiating benign and malignant lung diseases.Single-parameter ADCslow and DDC have a higher value in distinguishing benign and malignant lung diseases.The diagnostic value of biexponential model combined with stretched-exponential model in distinguishing benign and malignant lung diseases is superior to single parameter differential diagnosis. |
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